Answer
$2\sqrt{7}$
Work Step by Step
Let us simplify the expression $\sqrt{28}-3\sqrt 7+\sqrt{63}$
The given expression can be re-written as:
$\sqrt{28}-3\sqrt 7+\sqrt{63}=\sqrt{(7)(4)}-3\sqrt 7+\sqrt{(9)(7)}$
or, $\sqrt{28}-3\sqrt 7+\sqrt{63}=\sqrt{7}\sqrt{4}-3\sqrt 7+\sqrt{9}\sqrt{7}$
or, $\sqrt{28}-3\sqrt 7+\sqrt{63}=\sqrt{7}(2-3+3)$
or, $\sqrt{28}-3\sqrt 7+\sqrt{63}=2\sqrt{7}$
